Hot water heater

ABSTRACT

A HEATING DEVICE HAVING A VERTICAL FLUE THE EXTENDING THROUGH A WATER TANK. BAFFLE MEANS ARE DISPOSED WITHIN SERVING TO BOTH RETAIN AND RADIATE ABSORBED HEAT. A FLUE SERVING TO BOTH RETAIN AND RADIATE ADSORBED HEAT. A FLUE COLLECTOR SURROUNDING THE TANK TOP RECEIVES THE GASES FROM THE TUBE AND DIRECTS THE GASES OVER THE TANK TOP WALL BEFORE DISCHARGE THROUGH A VENT DUCT.

Sept. 20, 1971 H. E. THOMPSON HOT WATER HEATER 2 Sheets-Sheet 1 Filed July 1, 1969 INVENTOI? mey z mmpsw I 1/ ATTOPN Y P 0, 1971 H. E. THOMPSON 3,605,702

HOT WATER HEATER Filed July 1, 1969 2 Sheets-Sheet 2 ZNVE/VYOR #n/ny E. 77/001, 50!

I I! BY AT NE) United States Patent Qflice 3,605,702 Patented Sept. 20, 1971 3,605,702 HOT WATER HEATER Harry E. Thompson, Steubenville, Ohio, assignor to Peerless Division, Dover Corporation, Louisville, Ky. Filed July 1, 1969, Ser. No. 838,218 Int. Cl. F22b 7/00 US. Cl. 122-234 16 Claims ABSTRACT OF THE DISCLOSURE A heating device having a vertical flue tube extending through a water tank. Baffle means are disposed within the flue tube and includes flue gas directing elements serving to both retain and radiate absorbed heat. A flue collector surrounding the tank top receives the gases from the tube and directs the gases over the tank top wall before discharge through a vent duct.

This invention relates generally to a heating apparatus, and more particularly to a device specifically adapted to provide. hot water.

In the outfitting of travel or mobile homes the need arises for the provision of a compact, yet highly eflicient means for providing a supply of hot water. Such a device must necessarily be of a small size in view of the relatively limited space available in this environment, and at the same time must permit ready installation within the enclosure. This space limitation will be appreciated when realizing that small water heaters as used in the subject field are usually installed underneath trailer bunks and sinks or within the lower portion of clothes closets or seating spaces, all of which areas will be understood to be significantly limited in height. Accordingly, many prior known devices have relied upon a horizontal combustion or flue tube positioned within a similarly disposed heat exchanger tube within the water tank. The use of a central vertical internal flue has been practiced for many years in the larger capacity domestic form of water heaters wherein the height of the tank and flue is clearly adequate to provide a sufiicient heat exchange surface area but until the present invention it has been difiicult to provide a completely satisfactory unit utilizing a vertical internal flue tube in a water tank having a lateral dimension substantially greater than the height thereof. In the case of a gas-fired heater adequate means must also be provided to insure fresh air inlet and exhaust gas venting without necessitating special modification of the enclosure walls and without any bulky assembly protruding from the outside of the enclosure wall.

In order to achieve a satisfactory capacity of hot water and/or to obtain acceptable recovery rates, many of the prior known devices have been somewhat limited in capacity in view of the restricted area available for the hot water heater. Depending upon the size of the enclosure, it is usually desirable to provide a heater having a hot water tank with a capacity of anywhere from three to eighteen gallons. By the present invention a novel arrangement is offered comprising a substantially cylindrical water tank having a top and bottom configuration uniquely combined with a vertically extending heat exchanger tube including a novel combustion chamber baffle assembly therein such that the heated flue gases are directed through a circuitous path therethrough prior to exiting into an overlying flue collector. The baifle assembly includes means for the absorption of a large percentage of the heat contained in the travelling flue gases as well as means for encouraging the subsequent radiation thereof in a horizontal outward direction towards the surrounding wall of the heat exchanger tube, while the flue collector is arranged to further direct these flue gases after leaving the heat exchanger tube, over and around the entire top wall of the Water tank prior to discharge through a flue outlet.

The foregoing structure is associated with a sealed combustion and vent system wherein air is drawn from outside the enclosure to support combustion within the combustion chamber and the flue. products are discharged into the ambient atmosphere outside of the enclosure such that the air within the enclosure and surrounding the hot water heater remains undisturbed during operation of the invention. Means are included to insure the above operation even under extreme wind conditions.

Accordingly, one of the objects of the present invention is to provide a hot water heater including a water tank fully encapsulated within an insulated housing and having a new and improved combustion chamber provided with a heat retaining and radiating baflle assembly.

A further object of the present invention is to provide an improved hot water heater including a water tank having a heat exchanger tube extending throughout the entire vertical height thereof and provided with a baflle assembly therein having means imparting a circuitous path to flue gases passing therethrough.

Still another object of the present invention is to provide a hot water heater having a water tank provided with a vertically extending heat exchanger tube and in cluding a flue collector enclosing the top surface of the water tank and directing flue gases entering the same in a circular path over the top surface of the water tank prior to exiting into the atmosphere.

Another object of the present invention is to provide a gas-fired hot water heater having a water tank provided with a vertical heat exchanger tube and including a baffie assembly therein provided with foraminous means for absorbing heat from flue gases directed therethrough and imperforate means for radiating heat absorbed by said foraminous means toward the heat exchanger tube.

Another object is to provide a gas-fired hot water heater including a water tank having a lateral dimension substantially greater than the vertical height thereof and provided with a vertical combustion and flue chamber having baffle means for directing heated flue gases through a circuitous path therethrough.

With these and other objects in view which will more readily appear as the nature of the invention is better understood, the invention consists in the novel construction, combination and arrangement of parts hereinafter more fully described, illustrated and claimed.

A preferred and practical embodiment of the invention is shown in the accompanying drawings, in which:

FIG. 1 is a top perspective view of the hot water heater according to the present invention.

FIG. 2 is a front elevation of the hot water heater shown in FIG. 1.

FIG. 2a is a perspective view, partly broken away, of the outside cover used with the present invention.

FIG. 3 is a top plan view of the hot water heater of FIG. 1, with the top of the housing removed.

\FIG. 4 is a top plan view of the flue collector.

FIG. 5 is a side elevation, partly in section, of the hot water heater of the present invention.

FIG. 6 is a fragmentary perspective view of the vent duct comprising the flue outlet and draft deflector.

FIG. 7 is a top plan view of the baffle assembly.

FIG. 8 is an elevational view, with portions broken away for clarity, of the baflle assembly.

FIG. 9 is a bottom sectional view of the baffle assembly of FIGS. 7 and 8.

FIG. 10 is a bottom plan view of a modified baflle assembly construction.

Similar reference characters designate corresponding parts throughout the several figures of the drawings.

Refierring now to the drawings, more particularly FIGS. 1 and 5, the hot water heater of the present invention will be seen to include an outermost housing generally designated H, having horizontal top and bottom walls 1 and 2, respectively, joined together by a vertically disposed partially curved side wall 3 to provide an outwardly directed opening 4 formed by the parallel spaced apart ends of the side wall and the vertically coplanar ends of the top and bottom walls. Disposed within the housing H, but isolated from all adjacent walls thereof, is a unitary water tank T, the configuration of which when viewed in top plan will be seen to be circular. The tank T is of a generally flattened shape such that the lateral dimension thereof is substantially greater than the vertical height and is preferably constructed to provide a center section 5 having a cylindrical vertical side wall 6 and includes a top section 7 and a bottom section 8. Both the tank top wall 9 and bottom wall 10 provide surfaces which will be seen to be substantially elliptical in configuration when viewed in side vertical section and have highest and lowest points, respectively, axially aligned with the center axis 11 of the overall tank T, as shown in FIG. 3 of the drawings.

The above described tank T may be supported in any suitable manner within the confines of the housing H and is adequately insulated from the side wall 3 thereof by means of any suitable insulation 12. The tank is positioned sufiiciently high within the housing to provide a fresh air chamber A between the tank bottom and housing bottom. Extending throughout the vertical height of the tank is 2. preferably cylindrical heat exchanger or flue tube 13 which, as will be seen from FIGS. 3 and 5, is eccentrically disposed with respect to the center axis 11 of the tank and is positioned a short distance from the tank vertical side wall '6. The line tube 13 will be understood to be adequately sealed at both its upper and lower extremities where the tube intersects the tank top wall 9 and bottom wall 10 such that a single water chamber 14 is provided within the tank interior. Cold water is admitted to the water chamber 1 4 by means of a cold water inlet pipe 15 having its terminal portion preferably located juxtaposed the center axis 11 of the tank bottom wall 10 which is the lowest point of the water chamber '14, while a hot water outlet 16 is included through the upper portion of the tank side wall 6 adjacent the tank top section 7. A gas burner B is included within the interior of the housing H and positioned adjacent the lower opening of the flue tube 13 and will be understood to be connected to a suitable source of fuel such as LPG or natural or artificial pressurized gas, by any well known means.

Were the tank as described up to this point operated, it would be readily apparent to those skilled in the art that very little heat transfer would occur as a result of the heated products of combustion travelling upwardly through the relatively short line tube 13 since a very small amount of heat could be extracted from the upwardly travelling flue products through the limited height of the tube 13. The present invention, however, includes the provision of a unique baflie assembly, generally designated 17, which is adapted to be readily inserted and removed from the interior of the heat exchanger tube 13 and preferably occupies the majority of the vertical extent thereof. The principal purpose of this bafile assembly 17 is to substantially increase the heat transfer characteristics of the travelling hot flue gases such that the maximum amount of heat is extracted from these gases and directed to the wall of the heat exchanger tube in order to adequately heat the water in the chamber 14. The bafile assembly will be seen to comprise an inner cylinder 18 which is imperforate and includes an enclosed bottom wall 19 and an open top defined by the top rim 20. This inner cylinder 18 is adapted to be supported within the line tube 13 and in a concentric manner therewith by means which will become apparent hereinafter.

Surrounding the inner cylinder 18 in a concentric manner is a circular outer cylinder 21 which is formed of an open or foraminous material, most preferably expanded metal such as expanded metal lath. The top of this outer cylinder 21 is secured to a horizontally disposed collar 22 having a circular rim 23 providing a close mating fit within the periphery of the flue tube 13 and including a central flue opening 24 concentrically disposed with respect to the collar 22 and flue tube 13 but of a smaller diameter than that of the inner cylinder. The collar flue opening 24 is bounded by a downwardly extending flange 25, the lower edge 26 of which will be seen to be disposed at a horizontal plane significantly above the top rim 20 of the inner cylinder 18.

Any suitable means may be utilized to interconnect and thus support the inner cylinder 18 within the remaining structure of the baflle assembly 17. As shown in FIG. 9, a plurality of channel strips 27 are attached to the outer surface of the inner cylinder 18 on the one hand, while the foraminous outer cylinder 21 it attached to the opposite edges of each of these channel strips 27 such that the two cylindrical members will be maintained in a concentric or spaced apart relationship.

FIG. 10 illustrates another manner of supporting the two cylindrical elements in a concentric relationship. In this modification the outer cylinder 21a is initially fabricated to provide a plurality of inwardly, as well as outwardly, directed projections or VS 28. The points of the inwardly projecting Vs are suitably attached to the outer surface of the inner cylinder and serve to join the two cylinders, while the outwardly projecting Vs insure that the complete baflle assembly 17 will be properly concentrically located when positioned within the flue tube 13. It will thus follow that the outermost points of the downwardly projecting Vs 28 should extend to the same radius as the rim 23 of the bafiie collar 22 and it has been found that by mounting the outer cylinder 2101 at a substantially medially disposed location between the outer periphery of the inner cylinder 18 and the inner periphery of the flue tube 13 there will be provided the most eflicient operation of the device according to the manner as will now be described.

The foraminous material comprising the body of the outer cylinder 21 or 21a must meet certain requirements 1n order to exhibit the ultimate in heat extraction and radiation. A flattened expanded metal product is highly unsatisfactory as this would not present adequate radial projections into the path of the upwardly travelling heated flue products. Thus it will be understood that the [outer cylinder material should provide an expanded metal composition presenting a plurality of radially extending or laterally inclined members which in efiect project into the path of the moving flue products on both sides of the cylinder 21 or 21a in order to retard the gas travel while extracting the maximum amount of heat therefrom. It has been found that the smallest available diamond shape i serves most satisfactorily for the expanded metal as this arrangement provides the greatest possible number of lateral projections while still permitting the radiation of heat from the inner cylinder 18 through the outer cylinder to the flue tube 13.

With the bafile assembly 17 in position as shown in FIG. 5 it will be observed that when the water heater is turned on and combustion takes place above the burner B and within the combustion chamber portion C of the tube 13, the hot line gases will rise upwardly with the majority thereof initially striking the horizontal planar bottom wall 19 of the bafile assembly, thereby imparting a high temperature to this portion of the inner cylinder 18. The flue gases are then directed laterally and thence upwardly through the flue passage 29 defined by the space between the inner cylinder 18 and the flue tube 13.

As the still very hot flue gases move upwardly through this flue passage 29 a portion of the heat, of course, will be transferred to the adjacent heat exchanger tube 13 as well as the opposite and adjacent wall of the inner cylinder 18, but more importantly, it should be realized that a substantial portion of the heat carried by these gases will be absorbed by the intermediately disposed outer cylinder 21 or 21a within the flue passage. The preferred material of the outer cylinder 21 has been described as non-flattened expanded metal and the construction thereof will be readily apparent to those skilled in the art. As previously mentioned, such a material comprises a plurality of radially extending planar members disposed in an inclined manner with respect to either the vertical or horizontal plane and are usually interconnected to form a plurality of adjacent diamond shaped apertures. Such a construction readily lends itself to encouraging heat transfer thereto since the rapidly rising hot flue gases alternatively impinge successive inclined and angled portions of the outer cylinder on both sides thereof and thus make numerous radial and axial changes in direction of travel such that a circuitous path is followed by these gases between both sides of the outer cylinder and the maximum degree of heat transfer occurs. When the gases reach the upper portion of the flue passage 29 they abut the lower surface of the collar 21 and are then directed inwardly towards the outer surface of the depending flange 25 thereof. This action forces these gases back downwardly and inwardly of the rim 20 and into the inner chamber of the cylinder 18, as shown by the arrows in FIG. of the drawings. Thus heat transfer continues to take place from the hot flue gases as they are directed down into the interior of the cylinder 18 and prior to their subsequent emergence upwardly through the central flue opening 24 of the baffle assembly.

The preceding description of the flow of the heated flue gases through the baffle assembly 17 will be seen to encourage a maximum degree of heat transfer during this flue gas movement wherein the cylindrical outer wall of the inner cylinder 18 serves as a radiator, thus directing heat outwardly towards the heat exchanger tube 13. This outwardly radiating heat is influenced and further heated by passage through the foraminous outer cylinder 21 or 21a which has also been maintained at an elevated temperature level such that the cumulative heat now present will be directed toward the wall of the heat exchanger tube 13 to thus heat the water surrounding this tube.

Normally the heated products of combustion as they leave the top of the flue tube are directed to any suitable 'vent or exhaust leading to the atmosphere. However, the present invention provides additional heat transfer means in the form of a flue collector, generally designated 30, which is positioned in overlying relationship to both the top of the flue tube 13 and the entire tank top wall 9 in order to collect and specifically direct movement of gases issuing from the flue tube in a manner to further encourage extraction of heat therefrom to maintain water within the tank at an elevated temperature. The flue collector 30 comprises a cylindrical planar top wall 31 the diameter of which is substantially equal to that of the center section 5 of the water tank T. Depending from the periphery of the top wall 3 is a cylindrical vertically disposed side wall 32 the lower edge of which extends to a level corresponding to the juncture of the tank top section 7 and center section 5, as shown most clearly in FIG. 5 of the drawings. The flue collector 30 will thus be seen to comprise a hood arrangement enclosing the top section 7 of the water tank and is installed thereover in a more or less permanent manner such that the lower edge 33 of the flue collector side wall 32 provides a gas-tight seal with the water tank. Accordingly, an access cover 34 is provided through the top wall 31 of the flue collector at a point vertically aligned with the central axis of the underlying flue tube 13. As will be seen most clearly in FIG. 1, the housing H also is provided with an access cover 35 which is likewise vertically aligned with the central axis of the flue tube 13 such that by removal of the two access covers 34 and 35 it will be understood that the baflle assembly may be readily removed should servicing thereof be needed. In this regard a handle 36 may be attached to the collar 22 of the baffle assembly to facilitate installation and removal of the baffle assembly within the flue tube.

The vertical side wall 32 of the flue collector 30 extends completely around the tank top section 7 except for a small area disposed forwardly of the top of the flue tube 13. This point is left open to provide a flue exit 37 shown most clearly in FIG. 4, and communicates with a vent duct generally designated 38. This vent duct provides for both a flue gas outlet and a draft deflector and includes a horizontal flue outlet 39 communicating at its inner end with the flue exit 37 and at its outer lateral end with a flue product exhaust 40 discharging ultimately into the atmosphere. The outer surface of the vent duct includes a vertical deflector Wall 41 which will be seen to be inclined with respect to a line perpendicular to the normal direction of flue gas travelling through the outlet 39 such that gases striking the inner surface of the deflector wall 41 will be urged by this inclination towards the lateral flue product exhaust 40. Although the top, front and sides of the vent duct will be seen to be enclosed, except for the exhaust 40, it should be noted that the bottom surface thereof includes a transverse opening disposed intermediate the flue exit 37 aud vertical deflector wall 41 and serves as an air pressure relief inlet 42.

To further protect the surrounding environment, additional insulation is placed within the housing H between the top 31 of the flue collector 30 and the top 1 of the housing.

As initially indicated the preceding described construction is intended tobe utilized together with a sealed combustion system. In this respect it will be understood that the open end of the housing H as defined by the cavity 4 is adapted to be installed through a suitable opening in the Wall of the enclosure and subsequently provided with an overlying apertured cover or door 52 (FIG. 2a) communicating on its exterior with the atmosphere. To facilitate this installation through the enclosure wall appropriate mounting flanges 43 are provided at the free ends of the housing top, bottom and side walls as shown most clearly in FIGS. 1-3. The walls of the water tank T are isolated from the housing cavity 4 by a curved service wall 44 between which is disposed additional insulation 12 and through which extend the various accessory items well known to be associated with gas-fired water heaters such as a pressure relief valve 45, temperature control valve 46 and drain cock 47.

The eccentrically disposed arrangement of the heat exchanger tube 13 produces not only the aforedescribed improved circulation of water within the tank T and swirling circular movement of hot flue gases through the flue collector 30 over the tank top wall 9 but also provides ready accessibility to the burner B when located as shown in FIG. 3, wherein it will be seen that by ready removal of the burner access door 48 attached to the service wall 44 the burner B may be reacher 'very easily from the housing cavity 4. A multi-port type of gas burner B is illustrated in the drawings as this type is the most efiicient for producing the required heated gases for the tube 13 and also results in the quietest operation as opposed to other types of burners.

The all important objective of providing a balanced pressure system between the atmospheric air being supplied for combustion to the burner and the relief of the flue products of combustion even when the system is subjected to very high wind conditions is obtained by means of the present arrangement. The fresh air chamber A, which receives air for support of combustion through 7 the predetermined size of the burner access door 48 is protected from any sudden wind surges by means of the upstanding inlet bafiie 49 which extends lengthwise across the width of the housing opening 4 and is disposed intermediate the vertical plane of the mounting flanges 43 and the burner access door 48.

The outside cover or door 52 will be seen to include a plurality of horizontal louvers 53 extending across the top and a lesser number of similar louvers 54 extending across the bottom. The lower or inlet louvers 54 are located at a level juxtaposed the plane of the inlet baflle 49 and access door 48 thus providing a fresh air supply arrangement leading to the fresh air chamber A and burner B which is most resistant to extreme outside wind conditions. A greater number of upper or exhaust louvers 53 are located at a level juxtaposed the plane of the vent duct 38, the larger number of louvers at this point serving to exhaust the expanded volume of the heated flue gas and thus contributing to insure a balanced sealed combustion system.

A baflle assembly is included in the upper portion of the housing opening 4 and comprises an inverted U-shaped arrangement overlying the top of the vent duct 38 and includes a horizontal baflie 50 extending substantially the width of the opening 4 and joined to a pair of downwardly extending vertical baflles 5151, each spaced slightly from the adjacent housing side wall 3 and having its lower edge located below the bottom surface of the vent duct 38, as shown most clearly in F IG. 2.

I claim:

1. A hot Water heater including, a substantially cylindrical in plan water tank provided with a vertical heat exchanger tube extending through the interior thereof, said tank including a dome-like top section joined to a center section, a burner mounted adjacent the lower portion of said tube, a flue collector defining a horizontal chamber overlying the top of said tube and enveloping the exterior surface of said tank top section, said flue collector including a planar top wall joined to a circular side wall having its lower edge in fluid-tight engagement with said water tank substantially along the juncture of said tank top and center sections, a vent duct extending outwardly from said collector and a baflie assembly within said tube, said bafiie assembly including first means absorbing heat from hot flue gases passing upwardly through said tube, said baffle assembly including additional means absorbing and radiating heat itself as well as radiating the heat retained by said first means toward said tube.

2. A hot Water heater according to claim 1, wherein said baflie assembly first means comprises a foranu'nous metal element mounted in spaced relationship to said tube.

3. A hot water heater according to claim 1, wherein said baffle assembly additional means comprises an imperforate metal element disposed within said first means.

4. A hot water heater according to claim 1 wherein, said tube is eccentrically mounted with respect to the center aXiS of said tank.

5. A hot water heater according to claim 1 wherein, said water tank has a diameter substantially greater than its height.

6. A hot water heater including, a water tank provided with a vertical heat exchanger tube extending through the interior thereof, a burner mounted adjacent the lower portion of said tube, a flue collector defining a horizontal chamber overlying the top of said tube and the top of said water tank, a vent duct extending outwardly from said collector, and a bafiie assembly within said tube, said baffle assembly including first means absorbing heat from hot flue gases passing upwardly through said tube, said bafile assembly including additional means absorbing and radiating heat itself as well as radiating the heat retained by said first means toward said tube, said baffle assembly provided with a horizontal collar having a central flue opening and a peripheral rim providing a sliding mating fit within said tube, said first means comprising an outer cylinder of expanded metal having its upper edge attached to said collar, said additional means comprising an inner cylinder of imperforate metal having a bottom wall, and means joining said inner cylinder to said outer cylinder in a relationship spaced from said tube and one another.

7. A hot water heater according to claim 6, wherein said collar includes a flange depending from the edge of said central flue opening, and the diameter of said inner cylinder is greater than the diameter of said central flue opening while the top of said inner cylinder is disposed in a plane lower than the bottom of said flange.

8. A hot water heater according to claim 6, wherein said joining means comprises a plurality of metal strips between said inner and outer cylinders.

9. A hot water heater according to claim 6, wherein said joining means comprises a plurality of integrally formed V-shaped projections in said outer cylinder extending both inwardly toward said inner cylinder and outwardly toward said tube.

10. A hot water heater according to claim 1, wherein said bafiie assembly extends the majority of the vertical height of said tube.

11. A hot water heater according to claim 1, including a removable access cover on said flue collector top wall disposed over said tube and of a diameter no less than said bafile assembly.

12. A hot water heater including, a water tank provided with a vertical heat exchanger tube extending through the interior thereof, a burner mounted adjacent the lower portion of said tube, a flue collector defining a horizontal chamber overlying the top of said tube and the top of said water tank, a vent duct extending outwardly from said collector, and a bafiie assembly within said tube, said baffie assembly including first means absorbing heat from hot flue gases passing upwardly through said tube, said bafiie assembly including additional means absorbing and radiating heat itself as well as radiating the heat retained by said first means toward said tube, and a housing surrounding said water tank and provided with an open end adapted to pass through an enclosure wall, said vent duct projecting into said housing open end, said cover having a plurality of louvers therethrough to supply ambient outside air to said burner and to exhaust products of combustion from said vent duct to the outside air.

13. A hot water heater according to claim 12, wherein said cover louvers are located at a bottom level adjacent the horizontal plane of said burner and at an upper level adjacent the horizontal plane of said vent duct and a greater area of louvers is provided at said upper level to accommodate the expanded volume of flue gases exiting therethrough.

14. A hot water heater according to claim 12, including baffle means in the lower portion of said housing open end disposed between said cover louvers supplying outside air and said burner.

15. A hot water heater according to claim 12, including a deflector wall on the end of said vent duct disposed within said housing open end, said vent duct provided with a flue exhaust opening at one end of said deflector wall and an air pressure relief inlet through the bottom thereof adjacent said deflector wall and exhaust opening.

16. A hot water heater including, a water tank having a dome-like top section joined to a cylindrical center section, a vertical heat exchanger tube extending through the interior of said tank at a point eccentric with respect to the center axis of said tank, a burner mounted adjacent the lower portion of said tube, a flue collector having a horizontal top wall overlying the top of said tube and the top of said water tank, said flue collector including a sidewall extending from said top wall downwardly to said tank, the center of said top wall juxtaposed the top center of said dome-like top section whereby said flue collector defines an interior chamber extending horizontally and circularly about the top center of said dome-like tank top section, a vent duct extending outwardly from said flue collector, and a bafiie assembly within said tube, said baffie assembly including first means absorbing heat from hot flue gases passing upwardly through said tube, said baffle assembly including additional means absorbing and radiating heat itself as well as radiating the heat retained by said first means toward said tube, whereby as the hot flue gases leave said baffie assembly and exit from the top of said tube they are self-induced to circularly and horizontally pass through said flue collector interior chamber over said tank top section and thereafter exit through said vent duct.

References Cited UNITED STATES PATENTS Kramer 12217 Thompson 122156 Haas et al 122-155 Junkers 122367 Nussbaum 122367X 10 KENNETH W. SPRAGUE, Primary Examiner U.S. Cl. X.R. 

